In an arrangement of this type described in PKI Techmitt. 1987, SO. 1, p. 86, the core tubes in the form of glass capillaries are made comparatively thin, whereas the metal sleeves, which consist of a soft metal and can readily be worked, are very thick. When the plug pins are to be inserted into associated pin bushings consisting, for example, of a hard metal, and an easy motion is required also in a larger temperature range, comparatively large gaps must be made between the plug pin and the pin bushing to prevent at the highest temperatures clamping due to the plug pin expanding more considerably in the plug bushing. On the other hand, at low temperatures, gaps are formed that are too large and result in a misalignment of the LWG of the plug pin to the LWG of the plug bushing.